Trochanteric plate and artificial femoral head



June 29, 1954 CQLLISQN 2,682,265

TROCHANTERIC PLATE AND ARTIFICIAL FEMORAL HEAD Filed D80. 28, 1951 2 Sheets-Sheet l INVENTOR. dOl/l/ (OLA/30A, 05054350, firm/405111601150 AOMI/V/Sr/PATIF/X fornqy J. G. COLLISON June 29, 1954 TROCHANTERIC PLATE AND ARTIFICIAL FEMORAL HEAD '2 Sheets-Sheet 2 Filed Dec. 28, 1951 Patented June 29, 1954 TROCHANTERIC PLATE AND ARTIFICIAL FEMOR'AL HEAD John G. Collison, deceased, late of Baltimore, Md.,

by Marie B. Collison, administratrix, Baltimore, Md.

Application December 28, 1951, Serial No. 263,722

4 Claims. 1

The present invention relates to an improved supporting means for artificial femoral heads and in particular for an improved trochanteric plate for holding a supporting pin and an improved method of securing the head to the pin.

The primary object of the invention is to provide a trochanteric plate which will better conform to the femur bone and of such rigidity as to withstand the strain to which these plates are subjected.

Another object of the invention is to provide an improved means and method of securing the head member on its supporting pin.

Still another object of the invention is to provide for a limited movement of the head member toward the supporting plate in the event of absorption.

A further object of the invention is to provide means for spacing the artificial head outwardly from the adjacent portion of the femur.

While several objects of the invention have been pointed out, other objects and advantages will be more apparent as the nature of the invention is disclosed which consists in its novel construction, combination and arrangement of parts which are illustrated in the accompanying drawing and described in the following detailed description in which:

Figure 1 is a view in elevation of the trochanteric plate with the artificial head mounted thereon.

Figure 2 is a view of the outer face of the trochanteric plate.

Figure 3 is a view of the inner face of the trochanteric plate.

Figure 4 is a view in elevation of the connecting pin for connecting the plate with the femur head.

Figure 5 is a sectional view taken on line 5-5 of Figure 3.

Figure 6 is a view in elevation of the inner face of one of the spacing members located between the femur head and the outer end of the femur bone.

Figure 7 is a view of an artificial femur head having an aperture of uniform diameter.

Figure 8 is a view similar to Figure 7 showing the aperture of two diameters.

Figure 9 is a view similar to Figure 1 showing the trochanteric plate or brace attached to the femur in which the head is provided with the aperture having the two diameters.

Figure 10 is an enlarged fragmentary view of the head and pin illustrating the manner in which the head provided with the apertures having the two diameters is secured to the pin.

Figures 8 to 10 inclusive.

Referring in particular to the drawings, the device comprises of primarily an improved trochanteric plate I2 having a tubular portion I E, a head supporting pin it and an artificial head member [8.

The trochanteric plate, or brace [2' is formed in a slight taper downwardly and inwardly from its upper end, or at the point where the tube portion I 4 extends outwardly from the plate. The inner surface of the plate is of concave form, as shown best in Figure 5 to fit about the outer surface of the femur bone it. There is also provided at each end of the plate on the inner surface step members, or bearing surfaces 20 and 2|. The bearing surface 20 is located at the upper end of the plate adjacent the tube It and the bearing surface 2| is located at the lower end of the plate. Located along the plate are countersunk holes 22, through which screws 23 are placed to secure the plate to the bone.

The brace l2 and the tube portion M are preferably made from a single solid piece of material, however, the tube may be made separately and fixedly secured to the plate.

The portion I4 is of tubular form having the inner opening extending rearwardly through the plate, as shown at M. The tube portion extends laterally and upwardly from the upper end of the plate formin an obtuse angle with the plane thereof. The plate is slightly recessed about the tube at I3 to improve the fitting of the device to the femur.

Slidably receivable within the outer end of the tube is a head supporting pin It. This pin is preferably constructed with a cylindrical portion [6 adapted to freely slide within the outer end of the tube. The pin has a shoulder H for limiting the movement of the pin toward the plate upon over-absorption of the outer end of the bone. At the opposite end of the pin there is provided a cylindrical surface it" extending inwardly from the end of the pin for a predetermined distance. This surface It is adapted to be easily slidable into the aperture [8 provided in the head l8. Extended inwardly from the end of the pin is a shoulder or raised portion lt of approximately two thousandths of an inch. This shoulder is preferably a short cylindrical surface, but may be a long gradual taper and is adapted to fit with the aperture l3 of the head i8 under a drive fit.

A modified form of the invention is shown in The modification resides primarily in the head member. The aperture in the head of the modified portion is provided with a tapered, or cylindrical, step l8" which is of a slightly less diameter than the aperture 18. This step is approximately two-thousandths of an inch. The step is located inwardly from the open end of the aperture and at a distance sufficient to receive the outer end of the pin as shown best in the enlarged Figure 10. This structure enables the end of the pin to also have a drive fit into the head. In Figures 8 to the pin is shown held within the head about the areas l8 and 18 by a drive fit. This fixedly secures the head to the pin which is very important in this type of device in order that there will be no lost motion between the head and the pin.

When using the modified form of head, the pin is provided with an aperture leading from the end of the pin to the surface in rear of the area I8 in order to relieve the pressure from the end of the aperture H3 in the head when the head and pin are assembled.

The heads are made in various sizes, and also the pins come in different lengths, to meet different requirements. Located between the head and the upper end IQ of the femur there are provided one or more washers and 3 I. The washer placed next to the bone is preferably serrated on one side as shown at 30' in Figure 6 and also in Figures 1 and 9.

The plate l2 may also be used with either the surgical nail, or screw, in repairing femoral neck fractures.

The device is constructed preferably of stainless steel, or other suitable materials. It should also be noted that the bone structure is illustrated merely diagrammatically, and no attempt has been made to give an anatomically correct illustration thereof.

The tubular portion I4 extends outwardly and upwardly from the plane of the inner surface of the plate at approximately 135 degrees.

In applying the plate and the head member,

where it is necessary to replace the femoral head, the acetabulum is cleared of the femoral head as shown in Figures 1 and 9. Then a special drill jig is temporarily attached to the shaft of the femur and a hole is drilled all the way through the femoral neck. Then the trochanteric plate is permanently attached to the femoral shaft by the screws 23, with the tubular portion 14 of the plate extending into the hole in the bone. Then the portion iii of the pin i6 is inserted through the hole in the femoral neck into the tubular portion It. The washers, or spacers, 3B and 3| are then inserted over the end of the pin and the artificial head [8 inserted over the outer end of the pin. The pin moves freely over the surface [6 until it comes in contact with the step l6' which is approximately two-thousandths larger in diameter than the section IS". The next step is to place a punch, or other suitable instrument, against the end ll of the pin and by tapping the pin inwardly, the head will drive up over the shoulder, or step l6" and firmly secure the head to the pin. In the modified form the same procedure is followed. However, when the pin is driven into the head, the end of the pin is driven into the reduced diameter I8" of the head as shown best in Figure 10 at the same time as the outer end of the head is driven onto the enlarged portion 16" of the pin.

Also in applying the device a pin is selected that will allow for a space of approximately onequarter of an inch between the outer end of the tubular member and the shoulder IT, as normally the weight on the head member I8 will be carried through the spacers 3D and 3| to the upper end 4 19 of the femoral neck. However, if abnormal absorption occurs in the neck portion, the pin will move down into the tubular member until the shoulder l1 comes in contact with the outer end of the tube.

There should be no motion of the pin within the head member which is fixedly secured thereto by the drive fit.

The supporting surfaces 20 and 2! support the brace member [2 at each end and provide for better holding of the plate. The plate is also provide with a recess I2 between the two bearing surfaces to prevent cutting the bone to provide a smooth even surface for the entire length of the plate.

While the invention has been illustrated and described in its preferred form, it is not intended as a limitation as the scope of the invention is best defined in the appended claims.

What is claimed is:

1. In a device of the character described comprising a plate portion adapted to be secured along one side of the upper end of a femur bone, a tubular portion rigidly interconnected with the upper end of the plate and extending laterally through and forming an obtuse angle with the plane of the plate, and adapted to extend partly through an appropriate aperture in the upper end of the femur to receive a femur head supporting pin, the said plate being tapered downwardly and inwardly from its upper end, a bearing surface at each end of the plate adapted to rest against the femur bone and a recess extending along the inner surface of the plate between the two bearing surfaces.

2. In a device of the character described comprising a plate portion adapted to be secured along one side of the upper end of a femur bone, a tubular portion rigidly interconnected with the upper end of the plate and extending laterally through and forming an obtuse angle with the plane of the plate, a pin having one end adapted to slidably fit into the outer end of the said tube, the outer end of the pin having a cylindrical surface extending inwardly from the end of the pin for a predetermined distance, a shorter surface adjacent the inner end of the cylindrical surface of slightly larger diameter, an artificial femur head mounted on the outer end of the said pin, said head having an aperture extending inwardly from one side thereof, the diameter of the said aperture being such as to be freely slidable over the outer cylindrical surface of the pin and to receive the shorter enlarged surface under a drive fit.

3. In a device of the character described comprising a plate portion adapted to be secured along one side of the upper end of a femur bone, a tubular portion rigidly interconnected with the upper end of the plate and extending laterally from and forming an obtuse angle with the plane of the plate, a pin having one end adapted to slidably fit into the outer end of the said tube, the outer end of the pin having a cylindrical surface extending inwardly from the end of the pin for a predetermined distance, a shorter shoulder surface adjacent the inner end of the first cylindrical surface of slightly larger diameter, an artificial femur head mounted on the outer end of the said pin, said head having an aperture extending inwardly from one side thereof, the diameter of the outer portion of the said aperture being such as to slidably accommodate the outer end of the cylindrical surface of the pin to a predetermined point positioned 5 inwardly from the outer end of the aperture, the said aperture being slightly reduced in diameter from said point inwardly, the two diameters of the aperture adapted to accommodate the outer end of the pin and the enlarged shoulder portion of the pin under a drive fit, whereby the head is fixedly secured to the pin about two spaced drive fitted areas.

4. In a device of the character described comprising a plate portion adapted to be secured along one side of the upper end of a femur bone, a tubular portion rigidly interconnected with the upper end of the plate and extending laterally through and forming an obtuse angle with the plane of the plate, and adapted to extend partly through an appropriate aperture in the upper end of the femur to receive a femur head supporting pin, the said plate being tapered downwardly and inwardly from its upper end, a bearing surface at each end of the plate adapted to rest against the femur bone and a recess extending along the inner surface of the plate between the two bearing surfaces, said pin having one end adapted to slidably fit into the outer end of the said tube and a shoulder carried on said pin adapted to contact the outer end of the tube to limit its inward movement, the outer end of the pin having a cylindrical surface extending inwardly from the end of the pin for a predetermined distance, a shorter shoulder surface adjacent the inner end of the first cylindrical surface or" slightly larger diameter, an artificial femur head mounted on the outer end of the said pin, said head having an aperture extending inwardly from one side thereof, the diameter of the outer portion of the said aperture being such as to slidably accommodate the outer end of the cylindrical surface of the pin to a predetermined point positioned inwardly from the outer end of the aperture, the said aperture being slightly reduced in diameter from said point inwardly, the two diameters of the aperture adapted to accommodate the outer end of the pin and the enlarged shoulder portion of the pin under a drive fit, whereby the head is fixedly secured to the pin about two spaced drive-fitted areas and means positioned between the head and the outer end of the femur for positioning the head outwardly from the femur.

References Cited in the file of this patent The Journal of Bone and Joint Surgery, for January 1951, pp. 66-67. Copy in Scientific Library. 

